Population genetic analysis of human and animal populations have been used to study the genetic health and disease susceptibility of several species. Over 30 polymorphic human loci detected by 2DE have been described. The South African subspecies of cheetah was shown to be genetically depauperate insofar as it is monomorphic at 52 isozyme loci. Unrelated cheetahs also accepted skin grafts, a situation without precedent among outbred mammalian species. A devastating epizootic of the species of feline infectious peritonitis (FIP and RNA containing corona virus) was hypothesized to result from abrogation of a major histocompatibility complex (MHC) haplotype in T-cell stimulation. A sample of the east African cheetah subspecies showed similar genetic status and prompted us to hypothesize the occurrence of two severe population contractions in the natural history of the species. A molecular phylogeny of the great and lesser apes and man was derived based on genetic distance of 383 different proteins resolved by 2DE. A molecular phylogeny of the 37 species of the Felidae was constructed based on immunological distance using serum albumin. Similarly, a consensus phylogeny of the Ursidae Ailuropoda (giant panda) and Ailurus (lesser panda) was derived from distance matrices derived from three distinct molecular measures of genetic distance. A reconstruction experiment of organismal evolution using inbred mouse strain of defined genealogy demonstrated that morphologic and molecular genetic variation are uncoupled. A comparative analysis of cytological and linkage maps of mammals have indicated a noncontinuous tempo of chromosomal evolution in certain lineages (e.g., primates, felids) that are highly conserved in their chromosomal presentation, while others (rodents, lesser apes, canids) are chromosomally shuffled as if rapid saltatory cytological rearrangements occurred during the speciation events.